changes of eye-to-frame distance are made is shown by the following simple facts. According to the simple laws of perspective, if the eye is at thirty inches from the picture-plane or frame (as declared by a moon drawn of a little more than a quarter of an inch broad), a post or a man six feet high drawn on the canvas as three inches high absolutely and definitely means that that man or post is sixty feet away from the observer inside the picture. The height of the represented object is the same fraction of the real object as the eye-to-frame distance is of the distance of the observer to the real object. If by a two-inch moon the artist has thrown you back from the front plane of the scene to a distance of nineteen feet, then the six-foot post or man drawn as three inches high definitely asserts that it or he is 456 feet distant within the picture. So, too, if the church tower which cuts the moon is really sixty feet high and is drawn of two inches vertical measure in the picture, it is an assertion--when the moon is represented one quarter of an inch broad--that the church tower is 290 yards, or a sixth of a mile distant. If, on the other hand, other things remaining the same, the moon is drawn two inches in diameter, the church tower is now asserted to be eight times as far off, or about a mile and a third. Very generally these facts are not considered by painters. They represent the low moon (or sun) big because the erroneous mental impression is common to all of us that it _is_ big--that is, bigger, much bigger, than the high moon or sun, and they do not follow out the consequences in perspective of the pictorial increase of the moon's apparent diameter.